The present invention relates to a resin-packaged semiconductor device. More specifically, the present invention relates to a semiconductor device suitably used as surface-mounted on a substrate.
FIG. 18 and FIG. 19 show a prior art semiconductor device. The illustrated semiconductor device B is constituted as a light emitting device, and comprises a resin package 90, a semiconductor chip 93, a wire W, a first lead 91, and a second lead 92. The first and the second leads 91, 92 respectively include horizontal inner terminals 91a, 91b enclosed within the resin package 90, and outer terminals 91b, 92b exposed outside of the resin package 90. The outer terminals 91b, 92b have respective bottom surface portions 94a, 94b flush with a bottom surface 90b of the resin package 90. The semiconductor chip 93 is a light emitting element for example, and is bonded to the internal terminal 91a and sealed into the resin package 90. The wire W has a first end bonded to an electrode on an upper surface of the semiconductor chip 93 and a second end bonded to the inner terminal 92a, and is sealed into the resin package 90. The resin package 90 is made, for example, of a transparent epoxy resin not mixed with filler, and has an upper surface 90a formed with a lens portion 95 serving as a convex lens.
The semiconductor device B described above has following problems.
First, the wire W can fail if the semiconductor device B is surface-mounted on a substrate by means of a solder re-flow method. More specifically, as shown in FIG. 19, when the semiconductor device B is surface-mounted on a substrate 96, solder paste H is applied to electrode pads 97a, 97b on the substrate 96. Next, semiconductor device B is placed on the substrate 96 so that the bottom surface portions 94a, 94b of the outer terminals 91b, 92b are located on the corresponding electrode pads 97a, 97b. The substrate 96 and the semiconductor device B in this state is brought in a heating furnace and heated. The temperature in the heating furnace is about 240xc2x0 C. for example. Thus, the applied solder paste H is re-melted. Thereafter, the substrate 96 and the semiconductor device B are taken out of the heating furnace and allowed to cool, so that the solder paste H sets to fix the semiconductor device B onto the substrate 96.
In the series of operations as described above, at the cooling step which follows the re-melting step, the solder paste H becomes solid at a temperature of 183xc2x0 C. for example, fixing the first and the second leads 91, 92 onto the electrode pads 97a, 97b. However, at this particular point (at the temperature of 183xc2x0 C.), the resin package 90 is still soft, staying in a thermally expanded state, being in a course of thermal shrinkage with ongoing further decrease in the temperature. This is because the epoxy resin not mixed with filler has a glass transformation temperature of about 120xc2x0 C., which is lower than the setting temperature of the solder paste H.
If the resin package 90 shrinks after the first and the second leads 91, 92 have been fixed onto the electrode pads 97a, 97b, a shrinking force of the resin package 90 is exerted to the semiconductor chip 93 and the wire W which are connected to the first and the second leads 91, 92 respectively. This can cause the wire W to fail at a location of the bonding.
Secondly, according to the prior art, when light from the semiconductor chip 93 is condensed by the lens portion 95, it is desirable that there is a large space between the lens portion 95 and the semiconductor chip 93 in order to increase light condensing effect. This is because the light emitted from the semiconductor chip 93 advances in a certain diffusing angle. If a longer distance is provided between the semiconductor chip 93 and the lens portion 95, the light reaching the lens portion 95 becomes closer to a beam which is parallel to an optical axis of the lens portion 95.
However, according to the prior art, if the distance between the semiconductor chip 93 and the lens portion 95 is increased by increasing a thickness of the resin in between, then an overall size of the semiconductor device B has to be increased. On the other hand, as shown in FIG. 20, if a height of the inner terminals 91a, 92a in the resin package 90 is decreased, a thickness t of the resin beneath these inner terminals 91a, 92a has to be decreased in a wide range. This sacrifices strength of the resin package 90, making the resin package 90 susceptible to a crack.
It is therefore an object of the present invention to provide a semiconductor device capable of solving or reducing the above described problem in the prior art.
A semiconductor device provided by a the present invention comprises:
a resin package including an upper surface, a bottom surface opposed thereto thickness wise, a first side surface and a second side surface opposed to the first surface widthwise;
a semiconductor chip sealed in the resin package;
a wire sealed in the resin package and including a first end bonded to the semiconductor chip;
a first lead including a first inner terminal entering from the first side surface into the resin package and a first outer terminal connecting to the first inner terminal and exposed to outside of the resin package, the semiconductor chip being bonded to the first inner terminal; and
a second lead including a second inner terminal entering from the second side surface into the resin package and a second outer terminal connecting to the second inner terminal and exposed to outside of the resin package, a second end portion of the wire being bonded to the second inner terminal.
According to this semiconductor device, at least one of the first and the second inner terminals is bent in a direction of the thickness of the resin package.
Preferably, the semiconductor chip provides a light emitting element or a light receiving element, and the resin package is capable of transmitting the light.
Preferably, the resin package is made of an epoxy resin.
Preferably, the upper surface of the resin package is provided with a lens portion for condensing light.
Preferably, the first inner terminal is bent, whereby displacing a bonding portion of the semiconductor chip closer to the bottom surface of the resin package than is a location where the first inner terminal enters the resin package in the first side surface.
Preferably, the first inner terminal is provided with a slanted surface facing each of the semiconductor chip and the lens portion and being capable of reflecting light received.
Preferably, the second inner terminal is bent, whereby providing the second inner terminal with a slanted surface facing each of the semiconductor chip and the lens portion and being capable of reflecting light received.
Preferably, the first inner terminal is provided with a recessed surface surrounding the semiconductor chip, facing the upper surface of the resin package and capable of reflecting light received.
Preferably, the recess provided by the recessed surface is filled with a covering material softer than the resin package and capable of transmitting light. Further, the semiconductor chip is covered by the covering material.
Preferably, each of the first and the second inner terminals is bent, whereby displacing the bonding portion of the semiconductor chip closer to the bottom surface of the resin package than is a location where the first inner terminal enters the resin package in the first side surface, and displacing the bonding portion of the second end of the wire closer to the bottom surface of the resin package than is a location where the second inner terminal enters the resin package in the second side surface.
Preferably, each of the first and the second inner terminals has a crank-like shape.
Preferably, each of the first and the second inner terminals is bent, whereby displacing the bonding portion of the semiconductor chip closer to the upper surface of the resin package than is a location where the first inner terminal enters the resin package in the first side surface, and displacing the bonding portion of the second end of the wire closer to the upper surface of the resin package than is a location where the second inner terminal enters the resin package in the second side surface.
Preferably, the semiconductor chip and the wire are entirely covered by a material which is softer than the resin package when heated with the resin package for softening the resin package.
Preferably, each of the first and the second outer terminals has a bottom surface portion extending along the bottom surface of the resin package.
Preferably, the first and the second outer terminals are exposed respectively from the first and the second side surfaces to out side of the resin package.
Preferably, at least one of the first and the second outer terminals is exposed from the bottom surface of the resin package to out side of the resin package.
Other objects, characteristics, and advantages of the present invention will become clearer from the following description of embodiments to be presented with reference to the accompanying drawings.